#include <iostream>

using namespace std;

int main()
{
    int n, k;
    cin >> n >> k;
    int x, mx, db = 0, i = 1, mi = 0;
    cin >> x;
    mx = x;
    while(i < n){
        cin >> x;
        if(x > mx){
            mx = x;
            mi = i;
            db = 0;
        }

        else
            db ++;
        if(db == k){
            cout << mi + 1;
            return 0;
        }
        i ++;
    }
    cout << -1;
    return 0;
}